1. Field of Invention
The present invention relates to a catheter for treating a luminal system of a patient. Particularly, the present invention is directed to a catheter having a plurality of stiffening members to vary the stiffness along the length of the catheter body.
2. Description of Related Art
A variety of catheter devices are known in the art for treating the luminal system of a patient. Of such devices, many are directed to treating the cardiovascular system of a patient. One such cardiovascular system treatment includes percutaneous transluminal coronary angioplasty (PTCA); a procedure for treating heart disease. This procedure generally entails introducing a catheter assembly into the cardiovascular system of a patient via the brachial or femoral artery, and advancing the catheter assembly through the coronary vasculature until a balloon portion thereon is positioned across an occlusive lesion. Once in position across the lesion, the balloon is inflated to a predetermined size to radially compress against the atherosclerotic plaque of the lesion to remodel the vessel wall. Subsequently, the balloon is deflated to allow the catheter assembly to be withdrawn from the vasculature.
Often the site of the occlusive lesion is only reached by a tortuous pathway through the vasculature of the patient. The difficulty in accessing such regions requires that a successful catheter must be quite flexible to follow the tortuous path into the tissue, and at the same time, stiff enough to allow the distal end of the catheter to be manipulated from an external access site.
To address this problem, catheters having varied flexibility along their length have been developed. For example, each of U.S. Pat. No. 4,782,834 to Maguire and U.S. Pat. No. 5,370,655 to Burns discloses a catheter having sections along its length which are formed from materials having a different stiffness; U.S. Pat. No. 4,976,690 to Solar discloses a catheter having an intermediate waist portion which provides increased flexibility along the catheter shaft; U.S. Pat. No. 5,423,754 to Cornelius discloses a catheter having a greater flexibility at its distal portion due to both a material and dimensional transition in the shaft; and U.S. Pat. No. 5,649,909 to Cornelius discloses a catheter having a proximal portion with greater stiffness due to the application of a polymeric coating thereto.
Such conventional methods and systems generally have been considered satisfactory for their intended purpose. However, catheters still suffer from certain performance issues, such as by lack of pushability and kink resistance. Although solutions to this problem have been developed as discussed supra, there still remains a continued need in the art for a catheter having varied flexibility to enhance pushability, kink resistance and versatility. The present invention provides a solution for these problems.